In the related art, as this type of screen printer, there is proposed a screen printer in which a reflective photoelectric switch is attached to a squeegee holding device which can be moved parallel to the screen while holding a squeegee, and the screen printer measures an amount of solder on the screen based on a detection signal from the photoelectric switch (for example, refer to PTL 1). In this screen printer, when the printing is completed, the squeegee holding device is moved along the screen such that an optical axis of the photoelectric switch passes through the solder, and an interval (a movement distance) between two positions at which the detection signal of the photoelectric switch changes is calculated as a solder roll width, that is, the solder amount.
PTL 1: JP-A-2008-74054